Process for cleaning automobile radiators



and tetrasodium pyrophosphate.

Patented Jan. 12, 1954 PROCESS FOR CLEANING AUTOMOBILE RADIATORS Hugh C.De Hoff, Roselle Park, N. J., assignor to Standard Oil DevelopmentCompany, a corporation of Delaware No Drawing. Application October 11,1950, Serial No. 189,685

1 Claim. 1

This invention concerns a novel composition of matter suitable for useas a cleaning agent for the radiators of automotive type engines. Thecomposition of this invention comprises a combination of approximatelyequal parts of oxalic acid and ammonium oxalate, preferably inEornnationwith a detergent. This cleaning composition is to be employed in aradiator as an aqueous solution to remove iron rust. after which aneutralizing composition is preferably employed which comprises amixture of sodium carbonate The use of the indicated cleaningcomposition is effective in cleaning the radiator of engines to anextent heretofore unobtainable when employing conventional radiatorcleaners.

At the present time the radiator of an automotive type engine isprincipally constructed of ferrous material. However, soldered joints inthe radiator, to ether with connecting lines, are generally of such anature that copper is also present, either in the radiator or in linesassociated with the radiator. In the course of time, the interstices ofthe radiator become rusted so as to necessitate some means for removingthe iron rust which has formed. Consequently, it is necessary to providea cleaning agent capable of dissolving or removing iron rust in theradiator. At the same time it is necessary to minimize or eliminate theattack of this cleaning agent on copper compositions present in theradiator. It is therefore the object of this invention to provide anovel cleaning composition and technique capable of achieving theseobjectives.

It had been found that a cleaning composition consisting of a mixture ofoxalic acid and am-- monium oxalate is peculiarly effective in removingiron rust from a radiator. It is particularly notable that. in somemanner. these two compounds appear to exert a cooperative action so asto provide cleaning results not obtainable with equivalent amounts ofeither of the compounds individually. Thus, the combination of oxalicacid and am onium oxalate is effective to remove greater quantities ofiron rust from a radiator than either of these compounds alone whenemploying similar quantities.

Use of an acidic cleaning compound of the nature indicated, necessitatesprovision for neutralizing the acidic conditions provided by thecleaning solution. To solve this problem it has been found that sodiumcarbonate and tetrasodium pyrophosphate when employed in combination arepeculiarly efiective, not only for neutralizing the acidic conditions,but also in securing additional removal of iron rust. Consequently, itis a further aspect of this invention that once cleaning has beenconducted employing the combination of oxalic acid and ammonium oxalate,then neutralization and residual cleaning is afiected by employing acombination of sodium carbonate and tetrasodium pyrophosphate.

In addition to the above identified principles, it has furthermore beenfound that improved radiator cleaning is possible by incorporating asmall per cent of a suitable detergent with the cleaning compositioncomprising the oxalic acid and the ammonium oxalate. The detergentcompound is apparently effective in cooperating with the otherconstituents of the cleaning agent to facilitate the removal of rustfrom the radiator. It is probable that this action is related to freeingof the iron rust from oil or oil films which may be present in theradiator.

In order to evaluate the cleaning compositions and techniques of thisinvention a large number of actual tests were conducted employing avariety of cleaning agents and cleaning compositions. In these testsbadly corroded automotive radiators were subjected to different cleaningoperations. By the nature of this work it was impossible to securestrictly comparable quantitative results. Consequently, in testing anyparticular cleaning composition, the composition was emploved in manyradiators so as to average out diflferences in the condition of theseradiators.

Consequently, the observations to be presented hereafter are based onthe examination of cleaning results in literally scores of radiatorcleaning tests.

The results of these tests were determined in large part by qualitativevisual observations. Thus, it is effective in evaluating a cleaningcomposition, to visually note the quantity and nature of iron rust whichis removed when employing a given cleaning composition. At the sam time,the actual amount of iron rust freed from the radiator was weighed so asto provide an actual indication of the amount of rust removed from anyparticular radiator.

The actual cleaning technique employed was to first flush out theradiator concerned with fresh water. The radiator cleaning compositionwas then placed in the radiator and the engine was operated for a periodof 30 minutes. At the end of this time the cleaning solution was drainedfrom the radiator for determination of the amount of iron rust removed.Thereafter the radiator was flushed with water and the neutralizingsolution was then placed in the radiator.

Again the car engine was operated for at least 30 minutes while theneutralizing solution was contained in the radiator. Finally theradiator was drained of the neutralizing solution and was once moreflushed with water.

In conducting these tests, one pound of the particular cleaning solutionto be employed was dissolved in sufficient fresh water to fillthe-radiator to be cleaned. In general, the radiator capacity is 14quarts, although in some cases radiators contain as much as 16 quarts ofwater. After the cleaning operation, in the subsequent flushingoperations, the neutralizing agent, was employed by adding two ounces ofthe particular neutralizer to the radiator when filled with clean water.

In conducting tests of this naturethe following results were secured:

First, with regard to results obtained with different types of cleaningagents, it was found that in general about 0.3% to 1.2% of iron oxidewas removed from the radiator, based on the total weight of fluidcontained in the radiator. In a first series of tests in which oxalicacid alone was employed as the cleaning agent, it was found that therust was removed from the radiator in a caky form. In a second series oftests. employing ammonium oxalate as the cleaning agent, it was foundthat the iron rust was removed from the radiator in the form of a finepowder. In each case the extent of rust removal or radiator cleaning wasabout the same with either of these agents when employed individually.However, it was apparent from the nature of the rust removed, asindicated, that. the two agents attacked the rust of the radiator in asomewhat different manner. Consequently, a third series of tests wereconducted in which approximately equal parts, that is about /2 poundeach of oxalic acid and ammonium oxalate were employed. In tests of thisnature, applied to more than 60 automobile radiators, it was found thatthe combination of oxalic acid and ammonium oxalate was effective inremoving about 20 to 25% more rust than when the same oua'ntity ofeither chemical was employed by itself.

Tests of this same general character were then carried out with avariety of possible neutralizing agents. Of particular significance werethe tests conducted with sodium carbonate alone and with tetrasodiumpyrophosphate in combination with r sodium carbonate. In the case inwhich sodium carbonate was employed alone as a neutralizer,

it was found that a definite attack was made on copper present in theradiator. When the neutralizing solution was drained from the radiatorit was found to contain a substantial quantity of dissolved copper. Inaddition, it was noted that the neutralizing solution, consisting ofsodium carbonate alone, was ineffective in securing any additionalremoval of rust from the radiator; that is, in addition to'that removedby the prior use of the cleaning solution. However, in tests em loyingapproximately equal proportions of sodium carbonate and tetrasodiumpyrophosph'ate it was found that substantially no copper, or at worst,simply a trace of copper was removed from the radiator by theneutralizing agent. Furthermore, a definite quantity of loosened ironrust was in some manner removed from the radiator byutilization of thisspecific neutralizing composition.

employed having a weight of about 20 gms. These strips were treated toremove all iron oxide or rust from their surface. Thereafter the stripswere maintained in contact with water for a period of 24 hours to permitformation of a rust film. These strips were then placed in contact witha cleaning solution for a period of 24 hours. The solution was thenanalyzed to determine the amount of iron removed in the form of ironoxide by each of the cleaning solutions tested. It was established thatiron oxide, rather than iron, was the material removed by the cleaningsolution. In each case the particu-. lar cleaning agent employed wasdissolved in water to provide a cleaning solution of 3% concentration.

In a first series of tests ammonium oxalate was employed alone as acleaning agent for the prepared rusted strips. In a typical test usingthe ammonium oxalate alone the iron strip prior to treatment weighed21.7 gms. After 24 hour contact with the cleaning solution the ironstrip weighed 21.1 gms. indicating that the ammonium oxalate solutionalone was eflective in removing 0.6 gm. of iron oxide.

In a second series of tests a similar solution containing oxalic acidalone was employed. In this case the initial weight of the iron stripwas 21.? gms., and the treated weight 21.2 gms., indicating removal ofabout 0.5 gm. of iron oxide.

Finally, in a third series of tests, sufficient ammonium oxalate andsufiicient oxalic acid was dissolved in water to provide a 1 /2%concentration of each of these constituents. On treating rusted ironstrips with this cleaning agent, in

typical tests, it was found that a rusted iron strip having an initialweight of 23.2 gms., was reduced to a weight of 22.1 gms., aftertreatment, indicating rust removal of about 1.1 gms. of rust. Incomparing this example with the two preceding examples, it is apparentthat either oxalic acid or ammonium oxalate alone is capable of removingabout the same amount of rust. However, whenthe two chemicals are usedin combination, substantially twice the amount of rust 7 can be removedwhen employing the same total weight of cleaning agent.

As described therefore-the cleaning technique of this invention requiresa first step cleaning treatment employing a eo m binat i qn of oxalic931 5 51 emmqniumpxamte api fi 'ir equ'afil proportions. It isparticularly contemplated thatabout one pound of this composition shouldbe employed, or in other words, '/2 pound of each of the agents is to beused. It is apparent that the particular proportions of the two agentsmay be varied or that the total weight of the cleaning compound may bevaried. In a second step of the cleaning process, after sturing, aneutralizing agent is employed consisting of about equal proportions ofsodium carbonate and tetrasodium pyrophosphate. 'It is particularlycontemplated that about one ounce of each of these ingredients beemployed to provide a total weight oftwo ounces, although again .theproportions of these agents and the total quantities of the agents maybe somewhat varied. As indicated, it is also within the scope of thisinvention. to include a minor proportion, as for example'about 5%, of adetergent in the cleaning solution, in combination with the oxalic acidand the ammonium oxalate.

What is claimed is:

The process of cleaning the radiator of an automotive type enginecomprising the steps of dissolving about one pound of a compositionconsisting of about equal parts by weight of oxalic acid and ammoniumoxalate in water contained in said radiator, operating the engine for aperiod oi about 30 minutes, draining the said solution of oxalic acidand ammonium oxalate, filling the radiator with an aqueous solution ofabout two ounces of a composition consisting of about equal weightproportions of sodium carbonate and tetrasodium pyrophosphate, andthereafter draining this solution from the radiator.

HUGH C. DE HOF'F.

6 References Cited in the file of this patent UNITED STATES PATENTSNumber Name Date Smith Nov. 4, 1924 Peterson et a1 Apr. 10, 1934 Winninget a1 Jan. 23, 1935 Jochum et a1 May 23, 1939 Tremaine Feb. 22, 1949Eichwald Apr. 11, 1950 OTHER REFERENCES Chemical Formulary, Bennett,vol. 6 (1934), pgs. 454 and 492.

